How to Store Peptides
Proper storage is the difference between a potent peptide and an expensive vial of degraded amino acids. Peptides are biological molecules that degrade when exposed to heat, light, moisture, and contamination. Understanding storage requirements for both lyophilized (freeze-dried) and reconstituted peptides ensures you get the full potency from every vial.
Last updated: 2026-01-28
What You'll Need
Steps
Store lyophilized peptides at -20°C or colder
Unreconstituted (freeze-dried) peptides should be stored in a freezer at -20°C (-4°F) for maximum shelf life. They can also be refrigerated at 2-8°C for shorter-term storage (1-3 months).
Refrigerate reconstituted peptides at 2-8°C
Once mixed with bacteriostatic water, store the vial in the refrigerator at 2-8°C (36-46°F). Never freeze reconstituted peptides — ice crystals damage the peptide structure.
Protect from light at all times
UV and visible light degrade peptides. Keep vials in their original packaging, wrap in aluminum foil, or store in an opaque container. Never leave peptide vials in direct sunlight.
Prevent contamination with sterile technique
Always swab vial tops with alcohol before each use. Never touch the rubber stopper with your fingers. Use a fresh needle for each draw. Contaminated vials can grow bacteria that degrade the peptide and pose infection risk.
Label every vial clearly
Label each reconstituted vial with: peptide name, concentration (mcg/mL), date reconstituted, and discard date (28 days from reconstitution). This prevents using expired peptides.
Storing Lyophilized (Unreconstituted) Peptides
Lyophilized peptides are remarkably stable when stored correctly. The freeze-drying process removes water, which is the primary catalyst for peptide degradation.
| Storage Condition | Estimated Shelf Life | Best For |
|---|---|---|
| -20°C to -80°C (freezer) | 2-5+ years | Long-term storage |
| 2-8°C (refrigerator) | 6-12 months | Medium-term / current supply |
| Room temperature (20-25°C) | 1-3 months | Short-term only / transit |
| Above 25°C | Rapidly degrades | Avoid |
Most suppliers ship lyophilized peptides at room temperature with insulation — this is acceptable for transit periods of a few days. Upon receipt, immediately transfer to freezer or refrigerator storage.
Storing Reconstituted Peptides
Once reconstituted with bacteriostatic water, peptides are significantly less stable:
- Refrigerate at 2-8°C — the benzyl alcohol in BAC water inhibits bacterial growth but doesn't prevent peptide degradation, which accelerates at higher temperatures
- Use within 28-30 days — potency begins declining after reconstitution. Most peptides retain >90% potency for the first 4 weeks when properly refrigerated
- Never freeze reconstituted peptides. Water expansion during freezing creates ice crystals that physically damage the peptide's molecular structure
- Minimize temperature fluctuations — don't repeatedly take the vial out of the fridge for extended periods. Draw your dose quickly and return the vial
If using sterile water (without preservative) instead of BAC water, the solution should be used immediately or within 24 hours, as there is no preservative to prevent bacterial growth.
Signs Your Peptide Has Degraded
Discard any peptide that shows these signs:
- Cloudiness: A reconstituted solution should be clear. Cloudiness indicates peptide aggregation or bacterial contamination
- Color change: Most peptide solutions are colorless. Yellowing or browning indicates oxidative degradation
- Visible particles: Floating particles or sediment indicate degradation or contamination
- Unusual odor: A strong or unusual smell from a reconstituted vial may indicate bacterial growth
- Changed consistency: Gel-like or viscous solutions indicate peptide aggregation
When in doubt, discard the vial. Using degraded peptides at best wastes your time (reduced potency) and at worst introduces harmful breakdown products or bacteria.
Traveling with Peptides
Maintaining the cold chain during travel requires planning:
- Lyophilized peptides can travel at room temperature for 2-3 days without significant degradation. Use an insulated pouch for longer trips
- Reconstituted peptides need continuous refrigeration. Use a small insulated cooler with cold packs (not frozen solid — you don't want the peptide to freeze)
- Air travel: Peptides in their original vials with labeling are generally permissible in carry-on luggage. TSA allows medically necessary liquids. Having documentation (prescription or purchase receipt) is helpful but not always required
- International travel: Research the legal status of your peptides in the destination country before traveling. Some countries restrict peptide importation